The present disclosure relates generally to information handling systems, and more particularly to preventing logical loops between information handling systems in a physical loop configuration.
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Some information handling systems such as switches are configured to aggregate multiple links to the switch using Link Aggregation Groups (LAGs) in order to, for example, increase throughput beyond what a single link can sustain, to provide redundancy in the event one or more links fail, and/or to provide a variety of other LAG benefits known in the art. In some situations, such switches may utilize multi-chassis LAGs that aggregate links connected to different networking nodes. For example, Virtual Link Trunking (VLT) is a proprietary aggregation protocol provided by the Assignee of the present disclosure that may be used on Top Of Rack (TOR) switches to aggregate links to different networking nodes connected to the TOR switch. In some situations, a VLT LAG may be provided on a TOR switch for respective direct links to a plurality of networking nodes (“directly-linked networking nodes”), and that plurality of directly-linked networking nodes may be connected together by inter-chassis links (ICLs) to each other, as well as to one or more networking nodes that do not have a direct link to the TOR switch that is a part of the VLT LAG (“indirectly-linked networking nodes”).
The connection of directly-linked networking nodes and indirectly-linked networking nodes can raise a number of issues. For example, when an indirectly-linked networking node receives traffic that must be forwarded through the VLT LAG to the TOR switch, that indirectly-linked networking node must send that traffic through a directly-linked networking node in order to reach the VLT LAG. Thus, the traffic must be forwarded through every networking node between the indirectly-linked networking node and the directly-linked networking node (via the ICLs) until the traffic reaches the directly-linked networking node. However, when connecting the indirectly-linked networking nodes and directly-linked networking nodes with network cables to provide the ICLs and redundant connections, loop configurations may be formed. While physical loops may provide benefits such as redundancy, layer-2 logical loops resulting from those physical loops can consume the majority of network resources by rebroadcasting network traffic between the networking nodes in the loop configuration. The Spanning Tree Protocol (STP) is a layer 2 protocol that is often used to prevent network traffic from looping on networking nodes in a loop configuration. However, when the STP is utilized in a VLT system, some of the ICLs will be inactive unless a primary link fails. As such, networking nodes in loop configurations in a VLT system will include underutilized ICLs if the STP is used to prevent layer-2 logical loops.
Accordingly, it would be desirable to provide an improved loop prevention system.